Wireless telegraphy.



G. W. PIERCE. WIRELESS TELEGRAPHY. APPLIoATioN FILED 00T. 17,1906.

Patented June 1,1909.

8 SHEETS-SHEET 1.

l G. W. PIERCE. WIRELESS TELEGRAPHY.

APPLIOATIONFILED 00T. 17,1906.

Patented June 1, 1909.

3 SHEETS-SHEET 2.

G. W. PIERCE.

WIRELESS TELEGBAPHY.

yPlLIoATIoN FILED. 00T. 17,1906.

Patented June 1,1909.

8 SHEETS-SHEET 3.

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Wray,

VNITED STATES PATENT OFFICE. GEORGE PIERCE, OF OAMBRIDGEM-A-SSACHUSETTS, ASSIGNOR TO MASSACHUSETTS WIRE- LESS EQUIPMENT COMPANY, OF BOSTON, MASSACHUSETTS, A CORPORATION OF NEW YORK.

WIRELESS TELEGRAPHY.

Specification of Letters Patent. Application led October 17, 1906. Ser'iaINo. 339,296.

Patented .fune 1, 1909.

To all whom 'it may concern."

Be it known that I, GEORGE W.' PIERCE, citizen of the United States, and resident of Cambridge, county of Middlesex, Massachu` setts, have invented certain new and useful Im rovements in Wireless Telegraphy, of which the following .is a speciicatlon.

The invention relates to wireless telegraphy and more especially to the receiving station of a wireless telegraph system. v

The object of the invention is to rovide at' the receiving station simple and e cient a paratus' by which the operator may quicl y and conveniently bring a sharply resonant receiving circuit into resonance or tune with electro-magnetic waves 'of widely varying length or may utilize a dully resonant circuit inlisteningfor signals of which he does not know the periodiclty or may eliminate to a great extent the interference vdue to strong.

-disturbances as of nearby stations whose messages are not desired.

In producing an apparatus of simple and compact form which may be conveniently adjusted to secure any of the conditions specified, I employ certain constructions and combinations of parts-which may be employed with advantage in systems which do not embody all the features of the invention and which may or ma not be provided with inians for securing allr thevconditions specie eThe various. parts and connections included in the app/aratus embodying the various features o my invention may be constructed as a permanent part of a receiving station or may be so constructed and ar- `ran ed that 'the apparatus may be independent y manufactured and may be readily con nected with the cooperating parts of any receivin station. A d

' In the drawings the' various features ofthe invention are shown embodied in an apparatus which may be independently manufac-- tured and which is so mounted and arranged .that it may be readily connected with the other arts of the receiving system.

In t ese drawings- Figure 1- is a plan view 4of the box or casing by which the parts ofthe apparatus are carried, the top ofthe box being removed and the wiring connectin the various parts being omitted for the sa e of .clearness Fig. 2 is a sectional detail through one of the condensers. Fig. 3 is a aces for the sliding contacts L5.

front elevation vof the box. i Fig. 4 is a sectional view on line 4-4 Fig. 1 and Fig. 5 is a diagrammatic view showing the wiring by which the various parts are connected.

In the form of apparatus' illustrated the various parts of the apparatus are mounted in and upon a box or casing which may be placed or secured in any convenient posltion with relation to the parts with which connection is to be made. This a paratus v comprises an inductance coil whic may be connected in circuit with thel antenna; a transformer, the primarycoil of which is in series with the inductance coil; a condenser in series with the secondary coil of the transformer; a condenserl which may be connected in shunt about the primary coil ofthe transformer; and various connections and devices for varying the number of active turns of wire in the inductance and transformer-,coa for varying the number of active plates lin the condensers, and for regulating the use of the various parts.

`The, inductance coil which may be connected with the antenna is indicated at L1. Thiscoil consists of a wire wound upon a cylinder AL of insulating material such for 1nstance as glass. The cylinder is supported between two heads L'which are connected together byv suitable tie rods La. v

The turns of wire in the coil L1 are separated and covered with insulating material, except along the spaces L4 which extend lonitudinally of the coil and form bearing sur- The 4contacts L5 aresecured upon a slide L6 which is mounted upon guide rods L7 and is connected to the inner end of an operatin rod I. The rod I extends through a meta late I secured to the ou-ter facev of head 2 and extends beyond the front ofthe box-where its outer end is provided with va knob I2' by which the rod may be conveniently manipulated-bythe operator. They late I is connected b a wirei (Fig. 5) Wit the inner end of a bin ing post M which is mounted upon the side of the box. This binding post may be connected by means 'of a wire mwith an elevated conductor o'r antenna indicated at A (Fig..5). Y

By` sllding the rod I 1n and out the contacts L'may be moved longitudinally of the coil' Lto vary the number of active turns in the coil. f The rod may be graduated for convenien'ce in resetting the contacts for the purpose ofsecuring any given condition or adjustment of parts in using the apparatus.

The inner end of the inductance coil L is connected 'by means of a wire p3 (Fig. 5) with the inner end of a coil L2 which forms the primary coil of a high-frequency transformer.

The construction of the high-frequency transformer is clearly s hown in Figs. l and 4. This transformer consists of two cylinders O O of insulating material such as glass mounted one within the other between two heads O2. The heads O2 are secured together by binding rods O3. The primary coil L2 of the transformer is wound upon the inner cylinder O, while the secondary coil L3 of the transformer is wound upon the outer cylinder'. The insulation which covers and separates the turns of wire in the coil L2 is removed from the periphery of the coil at the points O4 to 'form bearing surfaces for the contacts P. The contacts P are secured upon a slide P2 which is'mounted upon guide rods P3 and is secured to the inner end of the operating rod P. The operating rod extends through a plate P4 secured to the face of the head O2 and projects through the front ofthe box where its outer end is provided with a knob P5 by which it may be conveniently manipulated by the operator. By sliding the rodP in and out the number of active turns of wire in the primary coil of the transformer may be varied.

The secondary coil Ls ofthe transformerlis 'wound upon the outer cylinder O and the in-l sulation separating and covering the coil is removed at the )oints O5 to form longitudinally extending caring surfaces for the contacts S. The contacts S are secured upon a slide S2 which is mounted upon guide rods S3 and is secured tothe inner end of an operating rod S. The rod S extends through a late S4 secured to the head O2 and extends eyond the front of the box where its outer end is provided with a knob S5 by which it may be conveniently manipulated by the operatorr By adjusting the rod S the number of active turns of wire in the secondary coil of the transformer may be varied.

rl"he rods P and S may be graduated for convenience in setting the parts to give' any desired adjustment.

vUpon the front end of the box two condensers indicated at SC and PC in Fig. 5, are mounted. These condensers are similar in construction and only o ne of these condensers will therefore be described in detail. The

condenser SC consists of a number of thin metallic plates s s superimposed one u on the other and se arated by thin sheets o insulating material Any suitable metal and any suitable insulating material may be employed but I prefer to usel thin copper plates separated by thin sheets of mica. In the construction shown the condenser is-provided with 16 metallic plates and each plate is provided with an extending strip through which electrical connection with the plate is made. The 16 plates of the condenser are divided into two series, the plates in one series alternating wit-h the plates in the other series.

.The strips s3 which extend from the plates s of one series are connected with the inner ends of a corresponding series of contacts s4 which are mounted in a circular series upon the front of the box. The strips S5 which project from the other series of plates s are bound together so that all the plates in this series are continually in electrical connection with each other.

The number of active plates in the con denser is varied by means of a fan switch C3 which is arranged to cooperate with the outer ends of the contacts S4. The switch C3 isprovided with a series of spring plates corresponding in number to the number of contacts s4 and is connected with an operating handle C4 mounted in the front of the box. The inner end of the operating handle C4 is connected by means of a wire s (Fig. e) with a plate S4 and through it with the rod S. By turning the switch C3 therefore to engage one or more of the contacts s2 the condenser may be connected in series with the secondary coil L3 of the transformer and by varying the numb'er of contacts engaged by the switch the number of active of this post forms one of the contacts of a switch which will be described hereinafter. From the post w2 a wire s12 leads to the inner end of a binding post R2.' This binding )ost projects beyond the side ofthe box wiiere it may be conveniently connected through a wire r2 with an indicator for electro-magnetic waves indicated at l (Fig. 5)./ Through these connections therefore the condenser SC may be connected in series with an indicator for electro-magnetic waves. The circuit through the secondary coilof the transformer7 condenser SC and indicator R, may be completed by connecting'the wire r which leads from the indicator to the outer end of a second binding post R mounted upon the side of the box; the inner end of which is connected througha wires13 with the inner end of the secondary coil L3.

The condenser PC is similar in construction to the condenser SC and comprises a of insulating material. The condenser may be thrown mto and out of action and the number of active plates in the condenser may be varied by means of a fan switch C2" similar in construction and mode of operation to the switch C3.

The switch C2 is connected by means of a wire 7 with the inner end of tl're'inductance or with the wire p3 leading from this coil to the primary coil of the transformer. The plates p 0f the condenser are connected by a wire p8 with the inner end of a post w mounted upon the side of the box, the outer end of the post forming one of the contacts for a switch to be described.

The rod P through which thev number of active turns of wire 1n the primary coil of the transformer is varied, is connected through a wire pA with a post 'w4 secured in the side of the box. To theouter end of the post wl one arm W of a vdouble switch W2 is pivoted. The other arm W of this switch is pivoted to a post w5 secured on the side of lthe box and this post is connected by a wire p with the inner end of a binding post G. This binding post projects beyond the side of the box where it may be conveniently. connected by means of a wire g with the earth or with an artificial ground or with a Wire leading back and connected to the lantenna to form a closed circuit.

-The contact arms 1V W( of the switch W2 are arranged to engage contact posts rw w or contact post-s 'w2 w3. The posts w 'w' are connected by a wire p5 and when the contact arms of the switchare in engagement with these' posts the wirep4 leading from the primary coil ofthe transformeris connected with the bindin post G through the wire p5 and wire p6. Vhen the contact arms of the switch are in engagement with the posts w2 fw the v virel p4 is 'in connection with the wire .s12 leading to the binding post R2 to which the indicator R is connected, while the binding post R to which the indicator is also connected is in electrical connection with the binding post Gthrou h the wire p9, switch arm W and wire p6. l hen the parts are thus connected therefore the secondary coil L2 is connected with the ground through the indicator It.

For the purpose of short circuiting the inductance coil a wire 'i' (Fig. l5) leads from the binding post M to a contact t2 so arranged that it may be engaged by the switch C2. When the switch C2 is in engagement with f the contact i2 the condenser PC is out of aci'- sharply resonant circuit in tune with a sendyprimary-coil L? of 'theL transformer.

ing station, the switch W2 will be in such po- .sition that the arms N 1V engage the contact posts fw w as indicated in Fig. 5. The switch C3 will be turned to engage one or more of the contacts s2. Vfith the parts thus adjusted the detector R will be in a closed circuit in which it is connected in series with the secondary coil L3 of the transformer and with the condenser SC. This circuit will be inductively connected with thevantenna circuit through the primary and secondary coils of the transformer. to resonance with a sending station sending out .comparatively short waves, lthe switch C2 will be engaged with the contact 'i2 thus rendering the condenser PC inactive and short circuiting theinductance coil L. The

,tuning will then be done by adjusting the rod l Jcci-vary the number of active turnsin the primary ccill'L2 and the secondary circuit w1ll be adjusted in resonance with the pri- In tuning the apparatus mary circuit by adjusting the rod S to vary the number of active turns of wire in the secondary coil L3 and'by adjusting the switch U3 to Vary the number of active plates in the condenser SC. In bringing the apparatus into resonance with stations sending longer waves, the switch@z will be disengaged from the contact I2 so that'the inductance L will be in circuit. The tuningv will be done by ladjusting the bars I and P- to vary the number of active' turns of wire in the inductance coil L and the primary coil L2 of the transformer. The secondary circuit will be adjusted to resonancewith the primary 'circuit as before. In tuning the a paratus to resonance with stations 'sending still.. Ylonger waves, the switch C2 will be enga yed with one or more ofthe contacts p2 thus lrin ing the condenser PC into circuit shunted aloutte l e tuning of the primary circuit will be effected by adjusting tlrerods P' and Iand also ad paratus may thus bythe various ad'ustments and by bringing into actionof the various parts of the apparatus, be tuned to resonance with waves of widely varying length. l j, A circuit of dull resonance may be secured for use in listening for signals the periodicity of which is unknown to the o eratorby swinging the switch W2 into position to engage the osts 'we w3 and opening the switch C3. Wit tector R is connected with the antenna circuit-in series with two inductance coils L L2 which 'are connected in series between the antenna and the detector. This circuit includes the antenna A, connecting wire m, wire ,coil L', wire s, coil L2, wire 4, switch arm W', Wire s, wne r2, detector Wire 1 wire p9, switch arm W', wire p", and wire g. In tuning this circuit to resonance with the sfefclondary circuit will also pass through the By properfadjustments of the parts included inductance coil,vmeans for bringing either ofwaves to be received, the rods I and P may be adjusted to vary thenumber of active turns of wire in the ,inductance coil L and in the coil L2 which under these conditions is also an inductance coil.

If it is desired to cut down the effect on the receiving instrument of sources of strong disturbances as of nearby stations whose messages are not desired, this may be done by engaging the switch N2 with the contact ieces '102 'w3 and adjusting the switch C3 to ring the condenser SC into circuit. iVith theconnections thus made the currents in he primary circuit will pass through the ctor R- and the currents induced in the indicator VR but in the opposite direction.

inthe primary and secondary circuits, the lcurrents may be thrown into or out of phase and their relative' intensities varied so that currents produced by undesired signals will tend to neutralize each other while the desired signals may be intensified.

Vhile I prefer to employ the specific form and arrangement of devices shown and described and to connect the various parts in the manner indicated,y it will be understood that these specific forms and arrangements and these specific connections may be varied without departingr from my invention.

,Without attempting to set forth in detail theI various forms in which the features of the invention may be embodied what I claim and desire to secure by Letters Patent is 1. AL tuning apparatus for wireless receiving stations, provided with a variable inductanc'e coil, means for connecting the same with the antenna, a high frequency transformer having a variable primary coil in series with said inducta'nce coil,-r a condenser, connections for shunting the condenser about the primary coil of the transformer, connections for short circuiting the these connections into circuit, and connections for connecting the secondary coil of the transformer with a detector for electromagnetic waves.

2. A tuning apparatus for wireless receiving stations, provided with an inductance coil, means for connecting the same with the antenna, means for varying the number of I active turns of wire in the coil, a primary i coil of a high frequency transformer in series i condenser in series with the secondary coil i consisting ol' a series of metallic plates,

means for varying the number of active, plates 1n the condenser, connect1ons for connecting the condenser and secondary coil in serles w1th a detector for electro-magnetic waves, a second condenser conslstlng of series of metallic plates, means for varying the number of active plates in the condenser, connections for connecting the primary of the transformer with the ground either directly or through the detector and for either connecting the latter condenser in shunt about the primary of the transformer or throwing it out of action, and connections for short circuiting the inductance coil at will.

3. A tuning apparatus for wireless receiving stations, provided with an inductance coil, means for connecting the same with the antenna, means for varying the number of active turns of wire in the coil, a primary coil of a high frequency transformer 1n series with the inductance coil, means for varying the number of active turns of wire in the primary coil, a secondary coil for the transformer, means for varying the number of active turns of wire in the secondary coil, a condenser in series with the secondary coil consisting of a series of metallic plates, means for varying the number of active plates in the condenser, connections for connecting the condenser and secondary coil in series with a detector for electro-magnetic waves, a second condenser consisting of series of metallic plates, means for varying the number of active plates in the condenser, connections for connecting the primary of the transformer with the ground either directly or through the detector and for either connecting the Alatter condenser in shunt about the primary of the transformer or throwing it out of action.

In Witness whereof, I have hereunto set my hand, this 15th day of October 1906.

GEORGE W. PIERCE.

In the presence of IRA L` FISH, KATHARINE A. DUGAN. 

